Purdue University Science Express,
Using the Red Tide Spectrometer to Measure Absorbance and Transmission…,
Page 1 of 6 6/2009
Using the Red Tide Spectrometer to Measure Absorbance and Transmission Through Sunglasses, Lenses, Plastics, and Fabrics
Purpose:
What percentage of visible and ultraviolet light is transmitted and absorbed by samples of sunglasses, various lenses, various plastics, or fabrics?
Introduction:
It is important and interesting to know what amount of ultraviolet light and visible light are transmitted or absorbed by materials like sunglasses or fabric. Sunglasses may or may not protect your eyes from ultraviolet radiation; fabrics may or may not protect your skin from sunburn; plastics milk containers may or may not lengthen the shelf life of milk. Since the Red Tide Spectrometer utilizes a small samples that fits into a cuvette, it cannot analyze intact sunglasses, chemistry safety splash goggles, or other large materials. This experiment provides a way to test some materials in SMALL samples that fit into cuvettes.
Materials:
Red Tide Spectrometer
LabQuest or LabPro
printer
premade samples of sunglasses, lenses, plastics, fabrics in cuvettes
Procedure:
1. Set up equipment as shown in diagram.
2. Connect spectrometer to LabQuest or laptop computer. Connect printer if necessary.
3. Follow directions to allow spectrometer to warm up and calibrate.
4. In the Experiment menu, select “Change units” to set up axes to record the data you want
(Absorbance vs. Wavelength, Percent Transmission vs. Wavelength, Intensity vs. Wavelength).
5. Insert sample. Be sure to orient cuvette in proper direction—arrow points toward the experimenter.
6. Observe spectrum. Record or print spectrum as necessary.
Additional experiments if your teacher directs:
7. Place both polarized lens samples in the same cuvette. Observe and record spectra.
8. Place three polarized lens samples in the same cuvette. Observe and record spectra.
Data: attach graphs of spectra as your teacher directs.
Data: design your own data table if your teacher directs.
List of samples:
1 = deionzed water
2 = tap water
3 = sunglasses sample #1
4 = sunglasses sample #2
5 = red filter from Sharkboy 3D glasses
6 = polarized sunglasses sample #1, horizontally sliced from lens
7 = polarized sunglasses sample #2, vertically sliced from lens
8 = polarized sunglasses sample #3, sample sliced at almost a 45o orientation from the lens
9 = student green chemistry splash goggles
10 = instructor grey chemistry splash goggles
11 = milk container
12 = ziplock baggie
13 = saran wrap
14 = transparency
15 = waxed paper
16 = cereal bag
17 = white cotton T shirt
18 = black cotton T shirt
19 = blue cotton bath towel
Conclusions and Activities: use complete sentences. (for regular students)
1. What results did you predict for each sample? How do your findings compare with your predictions?
2. What similarities are there among spectra? What differences are there among spectra?
3. Which materials permit ultraviolet light to be transmitted? Which materials block ultraviolet material?
4. Discuss the relationship between the transmitted wavelengths of light and the observed color of the sample.
5. During Spring Break, a friend claims that a T shirt if just as much protection from sunburn as sunblock lotion. What would you respond?
6. The same friend says that a beach towel would provide protection from sunburn as well. What would you respond?
7. Rank the plastics in order of the one that transmits the MOST ultraviolet light to the one that transmits the LEAST.
8. Rank the fabrics in order of the one that transmits the MOST ultraviolet light to the one that transmits the LEAST
9. What advice would you give to students who will do this experiment in the future?
10. What advice would you give to a teacher who wants her/his students to conduct this experiment in the future?
11. Summarize your results.
Additional Conclusions and Activities: use complete sentences (for advanced students)
12. Discuss the mathematical relationship between absorbance and transmittance.
13. Discuss the mathematical relationship between intensity and absorbance.
14. Explain differences (if any) between the spectra from one polarizing sunglass lens compared with two or three crossed polarizing sunglass lenses.Use vector diagrams to support your answers.
Classroom usage:
This experiment would be appropriate for students in Biology, Earth Science, Chemistry, and
Physics. It could be appropriate in a unit where students study electromagnetic radiation: how
cells and organisms respond to electromagnetic radiation, health and physiology, atmospheric
changes and weather, global warming, electron configurations and quantum mechanics, or
waves.
Curriculum Integration with Indiana’s Academic Standards:
Students can gain an undertstanding of the Standards instrumentation, technology, and sensors to investigate physical, chemical, and environmental factors.
Biologysome matching Standards are:
B 1.9, B. 1.10, B. 1.37, B. 1.44
Earth Science some matching Standards are:
ES. 1.9, ES. 1.13, ES. 1.18
Chemistrysome matching Standards are:
C. 1.37, C. 1.41
Physicssome matching Standards are:
P. 1.22, P. 1.23, P. 1.24, P. 1.25, P. 1.26, P. 1.27, P. 1.28
Teacher information, references, and useful websites:
See the other laboratory procedures here on the Participants link on this website for information about working with the Ultraviolet/Visible Spectrophotometer and how the spectrophotometer operates.
If you make your own slices of sunglasses or other plastic materials, wear safety goggles, work gloves, and use sturdy scissors or tin snips.
View Indiana’s Academic Standards and resources.
dc.doe.in.gov/Standards/AcademicStandards/index.shtml
Flinn Scientific provides our chemicals and important safety and reference information.
These sites provide detailed explanations for many Physics topics.
Red Tide Spectrometer setup Close-up view
Light pathDisplay on computer UV/VIS beautiful!
Debra Beck
Gregg Beck
6/2009